Ultrahigh melt flow styrenic block copolymers

ABSTRACT

A selectively hydrogenated block copolymer of general formula S-E-S, (S-E1)nX, or mixtures thereof is disclosed, where n has a value of 2-6, and X is a coupling agent residue. Before hydrogenation, S is a polystyrene block having a molecular weight of 4,400-5,600 g/mol, and E and E1 are polydiene blocks having molecular weights of 18,000-36,000 g/mol and 9,000 to 18,000 g/mol, respectively, selected from polybutadiene, polyisoprene and mixtures thereof, and having a total vinyl content of 60-85 mol %. After hydrogenation, the block copolymer has 0-10 percent of styrene double bonds reduced and at least 80 percent of conjugated diene double bonds reduced. The block copolymer has a solution viscosity of less than 80 centipoise (cP); a polystyrene content of 25-40 wt. % and up to 50 wt. % of diblock units of general formula S-E or S-E1.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.16/360,094, having a filing date of Mar. 21, 2019, which claims thebenefit of U.S. Provisional Application No. 62/647,218 filed Mar. 23,2018, the entire disclosures of which is incorporated herein byreference for all purposes.

FIELD

The disclosure relates to hydrogenated block copolymers and articlesmade thereof.

BACKGROUND

Conventional styrenic block copolymers in the prior art exhibitdesirable mechanical properties as required for certain applications,but difficult for processes such as molding, extrusion, 3D printing, andfiber spinning applications, and the like, due to their high viscosity.Therefore, it is a common practice to add substantial amounts ofpolyolefins, extending oils, tackifying resins and waxes and/or otherprocessing aids to make these block copolymers low viscosity therebyimproving their processability. However, additives often lead toinferior elastic properties and cause undesirable processing problemssuch as smoking and die build-up.

On the other hand, even if some conventional styrenic block copolymershave low viscosity and improved processability, they neither exhibitrequired mechanical properties nor aid in the preparation of molded andextruded articles.

Therefore, there is a need to produce styrenic block copolymers havingthe balance of low viscosity, improved elastic properties, and/orisotropic mechanical properties.

SUMMARY

In one aspect, a hydrogenated styrenic block copolymer is disclosed. Theselectively hydrogenated block copolymer has an S block and an E or E₁block, and a general formula: S-E-S, (S-E₁)_(n)X, or mixtures thereof,wherein: n has a value of 2 to 6, X is a coupling agent residue,molecular weight of the S block is 4,400 to 5,600 g/mol, a solutionviscosity of the block copolymer is less than 80 centipoise (cP),polystyrene content in the block copolymer is 25 to 40 wt. %, up to 50wt. % of diblock units in the block copolymer with a general formula S-Eor S-E₁; wherein prior to hydrogenation: the S block is a polystyreneblock, the E block is a polydiene block selected from the groupconsisting of polybutadiene, polyisoprene and mixtures thereof, andhaving a molecular weight of from 18,000 to 36,000 g/mol, the E₁ blockis a polydiene block selected from the group consisting ofpolybutadiene, polyisoprene and mixtures thereof, and having a molecularweight of from 9,000 to 18,000 g/mol, total vinyl content of thepolydiene block is 60 to 85%; and wherein subsequent to hydrogenation:0-10 percent of styrene double bonds in the block copolymer are reduced,and at least 80 percent of conjugated diene double bonds in the blockcopolymer are reduced.

In another aspect, the present disclosure relates to an article madefrom composition as described, with the article being selected fromfilms, 3D printed articles, sheets, coating, bands, strips, profile,molding, tubes, foam, tapes, fabric, thread, filaments, ribbons, fibers,and fibrous web, and tires.

In yet another aspect, the article is made by direct extrusion, capableof being used alone or in a laminate structure with a plurality of otherlayers. In yet another aspect, the article is a transparent, flexiblepart prepared by any of injection molding, slush molding, rotationalmolding, compression molding, and dipping.

DESCRIPTION

The following terms will have the following meanings unless otherwiseindicated.

“Vinyl content” refers to the content of a conjugated diene that ispolymerized via 1,2-addition in the case of butadiene, or via both1,2-addition and 3,4-addition in case of isoprene.

“Polystyrene content” or PSC of a block copolymer refers to the % weightof polymerized styrene in the block copolymer, calculated by dividingthe sum of molecular weight of all polystyrene blocks by the totalmolecular weight of the block copolymer. PSC can be determined using anysuitable methodology such as proton nuclear magnetic resonance (NMR).

The molecular weights can be measured with gel permeation chromatography(GPC) using polystyrene calibration standards, such as is done accordingto ASTM 5296-19. The chromatograph is calibrated using commerciallyavailable polystyrene molecular weight standards. The molecular weightof polymers measured using GPC so calibrated are styrene equivalentmolecular weights. The styrene equivalent molecular weight may beconverted to true molecular weight when the styrene content of thepolymer and the vinyl content of the diene segments are known. Thedetector can be a combination ultraviolet and refractive index detector.The molecular weights expressed herein are measured at the peak of theGPC trace, converted to true molecular weights, and are commonlyreferred to as “peak molecular weights”, designated as Mp. Unlessconverted to true molecular weights, as described above, the molecularweights refer to the styrene equivalent peak molecular weights. Unlessspecified otherwise, all of the reported molecular weights are truemolecular weights.

The order-disorder-transition temperature (ODT) refers to thetemperature at which the microdomain structure of the block copolymerbegins to disappear. ODT is defined as the temperature above which azero shear viscosity can be measured by dynamic rheology. ODTtemperatures can be measured using dynamic mechanical analysis (DMA),with temperature sweeps performed over various frequencies, wherein theODT is identified as the temperature where complex viscosity begins tocollapse to a single value independent of frequency at low frequencies

“Melt index” is a measure of the melt flow of the polymer according toASTM D1238 at 190° C. and 2.16 kg weight, expressed in units of grams ofpolymer passing through a melt rheometer orifice in 10 minutes.

ASTM D412 refers to the test method to determine the tensile propertiesof thermoplastic elastomers and vulcanized thermoset rubbers. A dumbbelland straight section specimens or cut ring specimens can be used. Forthe tests, a Mini D die with a dumbbell central width of 0.1 inch andthe length of the narrow parallel sided central portion of 0.5 inch isused to cut the specimens and a 50 mm/min. tensile rate is used.

Block Copolymer Composition:

In one embodiment, the composition comprises a selectively hydrogenatedblock copolymer having an S block and an E or E₁ block and having thegeneral formula: S-E-S, (S-E₁)_(n)X or mixtures thereof, and n has avalue from 2 to 6, or from 2 to 4, or a value of 2. The block copolymercan be linear sequential or coupled having two to six arms. In oneembodiment, the hydrogenated block copolymer of formula S-E-S has lessthan 10 wt. % for a diblock copolymer having the S-E formula, and theblock copolymer of formula (S-E₁)_(n)X has between 5 and 40 wt. % of adiblock copolymer of formula (S-E₁) formula.

Prior to hydrogenation, the S block of the block copolymers can be apolystyrene block having any molecular weight from 4,400 to 5,600.

Prior to hydrogenation, the E block or E₁ block is a polydiene blockselected from the group consisting of polybutadiene, polyisoprene andmixtures thereof. In one embodiment, the E blocks are a single polydieneblock. These polydiene blocks can have molecular weights that range from18,000 to 36,000. The E₁ block is a polydiene block having a molecularweight range of from 9,000 to 18,000.

In one embodiment, the general formula for the linear sequentialconfigurations is S-E-S, where the E block is a polydiene block,selected from the group consisting of polybutadiene, polyisoprene andmixtures thereof, having a molecular weight of from 18,000 to 36,000.

General formulae for the coupled configurations include:

wherein the E₁ block is a polydiene block, selected from the groupconsisting of polybutadiene, polyisoprene and mixtures thereof, having amolecular weight of from 9,000 to 18,000; and X is an alkoxy silanecoupling residue.

The block copolymer can be prepared by using a coupling agent that is atleast difunctional. A linear coupled block copolymer is made by formingthe first S block and E block and then contacting the diblock with adifunctional coupling agent. A radial block copolymer can be prepared byusing a coupling agent that is at least trifunctional. An example ofdifunctional coupling agents is methyl benzoate. Other useful couplingagents useful for forming radial block copolymers include, for example,silicon tetrachloride and alkoxy silanes, polyepoxides, polyisocyanates,polyimines, polyaldehydes, polyketones, polyanhydrides, polyesters,polyhalides, diesters, methoxy silanes, divinyl benzene,1,3,5-benzenetricarboxylic acid trichloride, glycidoxytrimethoxysilanes, and oxydipropylbis(trimethoxy silane).

In one embodiment, the coupling agent is an alkoxy silane of the generalformula R_(x)—Si—(OR′)_(y), where x is 0 or 1, x+y=3 or 4, R and R′ arethe same or different, R is selected from the group consisting of arylhydrocarbon radicals, linear alkyl hydrocarbon radicals and branchedalkyl hydrocarbon radicals, and R′ is selected from linear and branchedalkyl hydrocarbon radicals. The aryl radicals preferably have from 6 to12 carbon atoms. The alkyl radicals preferably have 1 to 12 carbonatoms, more preferably from 1 to 4 carbon atoms. Under melt conditions,these alkoxy silane coupling agents can couple further to yieldfunctionalities greater than 3. Examples of trialkoxy silanes includemethyl trimethoxy silane (“MTMS”), methyl triethoxy silane (“MTES”),isobutyl trimethoxy silane (“IBTMO”) and phenyl trimethoxy silane(“PhTMO”). Preferred dialkoxy silanes are dimethyl dimethoxy silane(“DMDMS”), dimethyl diethoxy silane (“DMDES”) and methyl diethoxy silane(“MDES”).

Block copolymer preparation: The block copolymers can be prepared byanionic polymerization of styrene and a diene selected butadiene,isoprene and mixtures thereof. The polymerization is accomplished bycontacting the styrene and diene monomers with an organoalkali metalcompound in a suitable solvent at a temperature from −150° C. to 300°C., preferably from 0° C. to 100° C. Examples of anionic polymerizationinitiators include organolithium compounds having the general formulaRLi_(n) where R is an aliphatic, cycloaliphatic, aromatic, oralkyl-substituted aromatic hydrocarbon radical having from 1 to 20carbon atoms; and n has a value from 1 to 4. Preferred initiatorsinclude n-butyl lithium and sec-butyl lithium. Methods for anionicpolymerization can be found in U.S. Pat. Nos. 4,039,593 and U.S. ReissuePat. No. Re 27,145, incorporated herein by reference.

In one embodiment, linear sequential block copolymers can be made bypolymerizing styrene to form a first S block, adding a diene to form anE block, and then adding additional styrene to form a second S block.

In another embodiment, a coupled block copolymer is made by forming thefirst S block and E₁ block and then contacting the diblock with adifunctional or trifunctional coupling agent. The process comprises acoupling reaction between a living polymer having the formula S-E₁-Liand the coupling agent as defined above, wherein Li is lithium.

The quantity of coupling agent employed with respect to the quantity ofliving polymers S-E₁-Li present depends largely upon the degree ofcoupling and the properties of the coupled polymers desired. Preferably,the coupling agent is used in an amount from 0.35 to 0.7 moles ofcoupling agent per mole of lithium, S-E₁-Li; or from 0.4 to 0.55 molesof coupling agent based upon the moles of lithium; or most preferably0.45 moles of coupling agent per mole of lithium.

The temperature at which the coupling reaction is carried out can varyover a broad range and often is the same as the polymerizationtemperature, e.g., from 0° to 150° C., from 30° C. to 100° C., or from55° C. to 80° C.

The coupling reaction is normally carried out by simply mixing thecoupling agent, neat or in solution, with the living polymer solution.The reaction period can be quite short, and affected by the mixing ratein the reactor, e.g., from 1 minute to 1 hour. Longer coupling periodsmay be required at lower temperatures.

After the coupling reaction, the linked polymers may be recovered, orsubjected to a selective hydrogenation of the diene portions of thepolymer. Hydrogenation generally improves thermal stability, ultravioletlight stability, oxidative stability, and weatherability of the finalpolymer.

Hydrogenation of Block Copolymer:

In one embodiment, the block copolymer is a hydrogenated blockcopolymer. The block copolymers can be selectively hydrogenated using ahydrogenation process as disclosed in U.S. Pat. Nos. 3,494,942;3,634,594; 3,670,054; 3,700,633; and Re. 27,145, incorporated byreference. Any hydrogenation method that is selective for the doublebonds in the conjugated polydiene blocks, leaving the aromaticunsaturation in the polystyrene blocks substantially intact, can be usedto prepare the hydrogenated block copolymers.

In one embodiment, the method employs a catalyst or catalyst precursorcomprising a metal, e.g., nickel or cobalt, and a suitable reducingagent such as an aluminum alkyl. Also useful are titanium based systems.The hydrogenation can be accomplished in a solvent at a temperature from20° C. to 100° C., and at a hydrogen partial pressure from 100 psig (689kPa) to 5,000 psig (34,473 kPa). Catalyst concentrations within therange from 10 ppm to 500 ppm by wt. of iron group metal based on totalsolution are generally used, and contacting at hydrogenation conditionsfrom 60 to 240 minutes. After the hydrogenation is completed, thecatalyst and catalyst residue will be separated from the polymer.

The microstructure relevant to the block copolymer can be controlled fora high amount of vinyl in the E and/or E₁ blocks, using a control agentknown in the art such as to diethyl ether and diethoxypropane duringpolymerization of the diene, as disclosed in U.S. Pat. No. Re 27,145 andU.S. Pat. No. 5,777,031, incorporated by reference.

Hydrogenation can be carried out under such conditions that at least 80%of the conjugated diene double bonds are reduced, and up to 10% of thearene double bonds are reduced.

The block copolymers are prepared so that they have from 60 to 85% vinylin the E and/or E₁ blocks prior to hydrogenation.

The styrene content of the block copolymer is from 25 wt. % to 40 wt. %.The coupling efficiency is in the range of 50-95% in one embodiment, andat least 80% in a second embodiment. In embodiments, subsequent tohydrogenation, from 0 to 10 percent of the styrene double bonds in the Sblocks have been hydrogenated.

Functionalization of Block Copolymer:

In some embodiments, the hydrogenated block copolymer is functionalizedto include an additional functional group or moiety. Exemplary monomersto be grafted onto the block copolymers include fumaric acid, itaconicacid, citraconic acid, acrylic acid, maleic anhydride, itaconicanhydride, citraconic anhydride, and their derivatives. The preferredgrafting monomer is maleic anhydride.

In one embodiment, the hydrogenated block copolymer is maleated bygrafting maleic anhydride onto the block copolymer. Maleation of theblock copolymer may be done by in the melt, in solution, or in the solidstate, and the process can be either continuous or batch. Various freeradical initiators, including peroxides and azo compounds can be used tofacilitate the maleation. In some embodiments, the block copolymercontains from 0.1 to 10, preferably 0.2 to 5 percent by weight ofgrafted monomer.

In one embodiment, the hydrogenated styrenic block copolymer isfunctionalized via reaction with maleic anhydride. Such functionalizedpolymers have additional polarity that makes them useful where adhesionto metals or other polar polymers is desired, such as in overmolding,tie layer, adhesive, and coating applications or in compatibilizationwith certain engineering thermoplastics such as polyamides or epoxyresins for example.

Optional Components:

In applications, the block copolymer compositions can also be admixedwith other block copolymers, olefin polymers, styrene polymers,tackifying resins, end block resins, engineering thermoplastic resins,and mixtures thereof.

Styrene polymers include, for example, crystal polystyrene, high impactpolystyrene, medium impact polystyrene, styrene/acrylonitrilecopolymers, styrene/acrylonitrile/butadiene (ABS) polymers, syndiotacticpolystyrene and styrene/olefin copolymers. Other polymer examplesinclude polyisobutylene polymers, substantially random ethylene/styreneor propylene/styrene copolymers, preferably containing at least 20weight percent copolymerized styrene monomer; styrene-graftedpolypropylene polymers; and other block copolymers such asstyrene-diene-styrene triblock, radial or star block polymers,styrene-diene diblock polymers, and the hydrogenated versions of thesepolymers.

Examples of engineering thermoplastic resins include thermoplasticpolyester, thermoplastic polyurethane, poly(aryl ether), poly(arylsulfone), acetal resin, polyamide, nitrile barrier resins, poly(methylmethacrylate), cyclic olefin copolymers, coumarone-indene resin,polyindene resin, poly(methyl indene) resin, polystyrene resin,vinyltoluene-alphamethylstyrene resin, alphamethylstyrene resin andpolyphenylene ether, in particular poly(2,6-dimethyl-1,4-phenyleneether), and mixtures thereof.

Suitable midblock compatible resins are C5 resin ((cyclopentadiene,cyclopentene, DCPD, piperylene, etc based resin)hydrogenated C5 resin,hydrogenated C5/C9 resins, hydrogenated C9 resins, terpene resin, rosinester resin, hydrogenated rosin ester resins or combinations thereof.

In embodiments, the hydrogenated block copolymer is blended with athermoplastic elastomer or a thermoplastic for use in tire treadformulation as a plasticizer.

In embodiments, the optional polymer is an olefin polymer, e.g.,ethylene homopolymers, ethylene/alpha-olefin copolymers, propylenehomopolymers, propylene/alpha-olefin copolymers, high impactpolypropylene, butylene homopolymers, butylene/alpha olefin copolymers,and other alpha olefin copolymers or interpolymers. In otherembodiments, the polymer is selected from ethylene/acrylic acid (EAA)copolymers, ethylene/methacrylic acid (EMAA) ionomers, ethylene/vinylacetate (EVA) copolymers, ethylene/vinyl alcohol (EVOH) copolymers,ethylene/cyclic olefin copolymers, polypropylene homopolymers andcopolymers, propylene/styrene copolymers, ethylene/propylene copolymers,polybutylene, ethylene carbon monoxide interpolymers (for example,ethylene/carbon monoxide (ECO) copolymer, ethylene/acrylic acid/carbonmonoxide terpolymer and the like.

Additives: The block copolymer compositions are characterized as havinglow viscosities and high melt flows that allow them to be easily moldedor continuously extruded into shapes or films or spun into fibers. Thisproperty allows end users to avoid or at least limit the use ofadditives that degrade properties, cause area contamination, smoking,and even build-up on molds and dies. While the hydrogenated blockcopolymers have such low ODTs and high melt indexes that they can beused to prepare articles without using processing aids, it is sometimesdesirable to use such aids and other additives. Examples include polymerextending oils, waxes, fillers, reinforcements, lubricants, stabilizers,and mixtures thereof. In embodiments, the additives are selected one ormore fillers such as TiO₂, CaCO₃, carbon black, or other pigments.

In one embodiment, the hydrogenated block copolymer is blended with0.001 to 10 wt. % of a mineral oil (paraffinic, naphthenic, oraromatic); or from 0.001 to 9 wt. %; 0.001 to 7.5 wt. %; and 0.001 to 5wt. % of a mineral oil.

Properties of Block Copolymer:

One characteristic of the hydrogenated block copolymers is that theyhave a low order-disorder temperature (ODT), with the ODT beingtypically less than 230° C. For ODT above 230° C., the polymer is moredifficult to process although in certain instances, ODTs greater than230° C. can be utilized for some applications, e.g., when the blockcopolymer is combined with other components to improve processing. Suchother components may be thermoplastic polymers, oils, resins, waxes orthe like. In embodiments, the ODT is from 150° C. to 230° C.; or from170° C. to 220° C.; or less than 230° C.

In embodiments, the hydrogenated block copolymers have a high melt indexallowing for easier processing, with a melt index from 80 g/10 min. to1300 g/10 min, preferably 200 g/10 min to 800 g/10 min at 190° C. and2.16 kg weight.

In embodiments, the hydrogenated block copolymer has a toluene solutionviscosity (at 25 wt. % and 25° C.) of greater than 10 cP, or less than80 CP; or from 15 to 80 cP, or from 20 to 50 cP.

In embodiments, the hydrogenated block copolymer has an elongation atbreak of at least 300%, or at least 450%.

In embodiments, the hydrogenated block copolymer has a tensile strengthof at least 1.5 Mpa; or at least 4 MPa; or at least 6 MPa; or 9 MPa orless, as measured on compression molded films according to ASTM D412.

In embodiments, the hydrogenated block copolymers have a hysteresisrecovery of greater than 35 percent and a permanent set of less than 35percent on the first retraction cycle after elongation to 300 percent.

INDUSTRIAL APPLICABILITY

The hydrogenated block copolymers are useful in a wide variety ofapplications either as a neat polymer or in a compound. Examplesinclude, for example, toys, medical devices, films, tubing, profiles, 3Dprinted article, sheet, coating, band, strip, molding, tube, foam, tape,fabric, thread, filament, ribbon, fiber, plurality of fibers and fibrousweb, overmolding applications for automotive parts, dipped goods such asgloves, thermoset applications such as in sheet molding compounds orbulk molding compounds for trays, hot melt adhesives, tie-layer forfunctionalized polymers, asphalt formulations, roofing sheets,geomembrane applications. The article can be formed in a processincluding injection molding, overmolding, dipping, extrusion,roto-molding, slush molding, fiber spinning, film making, 3D printingand foaming. In embodiments, the hydrogenated block copolymers are addedto rubber compositions for the use of making tire treads or innerlayers.

In embodiments, the hydrogenated block copolymers are for use in makingweb layers for the construction of an adsorbent personal hygiene productsuch as a baby diaper article, adult incontinence article, or femininenapkin article. In applications such as melt blown articles, thecomposition may contain an additional component of high flow polyolefinhaving a melt flow rate >40 g/10 min., polyisobutylene, polybutene,thermoplastic polyurethane, thermoplastic copolyester, oil, styrenicblock copolymer with melt flow rate <100 g/10 min., and/or mid-block orend block resin.

In embodiments, the hydrogenated block copolymers are used as anadditive, e.g., as a plasticizer, to thermoplastic compositions orthermoplastic elastomers in amount ranging from 0.1 to 90 wt. %; or from0.5 to 70 wt %, or 1 to 50 wt. %, or 5-35 wt. % based on the totalweight of the thermoplastic or thermoplastic elastomer composition.

In embodiments, the hydrogenated block copolymers are for use inadhesive formulations, e.g., a personal hygiene construction adhesive,elastic attachment adhesive, and hot-melt adhesive. The formulationscould comprise a blend such as 0 to about 80 wt. % poly-alpha-olefin, 10to about 60 wt. of a tackifying resin, and 10 to about 50 wt. % of thehydrogenated block copolymer. Examples of tackifying resins include C5resin (cyclopentadiene, cyclopentene, DCPD, piperylene, etc basedresin), hydrogenated C5 resin, hydrogenated C5/C9 resins, hydrogenatedC9 resins, terpene resin, rosin ester resin, hydrogenated rosin esterresins, or combinations thereof

EXAMPLES

The following examples are provided to illustrate the disclosure.

Example 1

A selectively hydrogenated block copolymer is prepared by anionicpolymerization of styrene and then butadiene in the presence of amicrostructure control agent followed by coupling and thenhydrogenation: a diblock polymer anion, S-E₁-Li, is prepared by charging6 L of cyclohexane and 342 g of styrene to a reactor. The reactortemperature set temperature was 50° C. 198 milliliters of a solution ofan approximately 12 wt. % solution of s-butyllithium in cyclohexane wasadded, and the styrene was allowed to complete polymerization. Themolecular weight of the polystyrene produced in this reaction wasdetermined to be 5,300 g/mol by GPC. 10 ml of 1,2-diethoxypropane wereadded, and then 715 g of butadiene were added at rates to allow thetemperature to remain 60° C. A sample collected at the end of thebutadiene polymerization had a styrene content of 36.5 wt. % and a vinylcontent of 79% basis ¹H NMR and an overall molecular weight ofapproximately 34,000 g/mol as determined by GPC. Followingpolymerization of the majority of the butadiene, and then 5.1 ml of MTMSwas added, and the coupling reaction was allowed to proceed for 60minutes at 60° C. 1.5 ml of an alcohol was added to terminate thereaction. The final product had a coupling efficiency of 92% and 72% ofthe coupled species were linear with the remaining 28 percent being3-arm radial.

A sample of the polymer was hydrogenated to a residual olefinconcentration of at least 0.15 meq/g and the catalyst was removed usingtechniques known in the art. The polymer was then recovered via steamstripping.

The selectively hydrogenated block copolymer was tested for composition,solution viscosity, and ODT. The results are in Table 1. Thehydrogenated block copolymer was also tested for mechanical propertiesand melt index. The results are in Table 2.

Example 2

A selectively block copolymer is prepared by anionic polymerization ofstyrene and then butadiene in the presence of a microstructure controlagent followed by coupling and then hydrogenation: a diblock polymeranion, S-E₁-Li, is prepared by charging 6 L of cyclohexane and 300 g, ofstyrene to a reactor. The reactor temperature was increased to 50° C.198 ml of a solution of an approximately 12% wt solution ofs-butyllithium in cyclohexane was added, and the styrene was allowed tocomplete polymerization at 60° C. The molecular weight of thepolystyrene produced in this reaction was determined to be 4,900 g/molby GPC. 8 ml. of 1,2-diethoxypropane were added, and then 720 g ofbutadiene were added at rates to allow the temperature to remain 60° C.A sample collected at the end of the butadiene polymerization had astyrene content of 32.4% wt and a vinyl content of 79% basis ¹H NMR andan overall molecular weight of approximately 34,000 g/mol. Followingpolymerization of the butadiene, 4.5 ml of DMDMS was added, and thecoupling reaction was allowed to proceed for 60 minutes at 60° C. 1.7 mlof 2-ethyl hexanol was added to terminate the reaction. The finalproduct had a coupling efficiency of 87% and 100% of the coupled polymerwas linear.

The polymer was hydrogenated to a residual olefin concentration of atleast 0.15 meq/g and the catalyst was removed using techniques known inthe art. The polymer was then recovered via steam stripping.

The selectively hydrogenated block copolymer was tested for polymercomposition, solution viscosity, and ODT. The results are in Table 1.The hydrogenated block copolymer was also tested for mechanicalproperties and melt index. The results are in Table 2.

Example 3

A selectively hydrogenated block copolymer is prepared by anionicpolymerization of styrene and then butadiene in the presence of amicrostructure control agent followed by coupling and thenhydrogenation: a diblock polymer anion, S-E₁-Li, is prepared by charging6 L of cyclohexane and 321 g, of styrene to a reactor. The reactortemperature was increased to 50° C. 198 ml of a solution of anapproximately 12% wt solution of s-butyllithium in cyclohexane wasadded, and the styrene was allowed to complete polymerization at 60° C.The molecular weight of the polystyrene produced in this reaction wasdetermined to be 4,900 by GPC. 10 ml. of 1,2-diethoxypropane were added,and then 638 g of butadiene were added at rates to allow the temperatureto remain 60° C. A sample collected at the end of the butadienepolymerization had a styrene content of 35% wt and a vinyl content of76% basis ¹H NMR and an overall molecular weight of 34,000 g/mol. Afterpolymerization of the butadiene, 3.6 ml of DMDMS was added, and thecoupling reaction was allowed to proceed for 60 minutes at 60° C. 2 mlof 2-ethyl hexanol 8.5 g, 0.1 mol per mol of Li) was added to terminatethe reaction. The final product had a coupling efficiency of 76% and100% of the coupled species were linear.

The polymer was hydrogenated to a residual olefin concentration of lessthan 0.15 meq/g and the catalyst was removed using techniques known inthe art. The polymer was then recovered via steam stripping. Thepartially hydrogenated block copolymer was tested for polymercomposition, solution viscosity, and ODT. The results are in Table 1.The hydrogenated block copolymer was also tested for mechanicalproperties and melt index. The results are in Table 2.

Example 4

A selectively hydrogenated block copolymer is prepared by anionicpolymerization of styrene followed by butadiene in the presence of amicrostructure control agent and then styrene again. The resultingpolymer is a linear triblock with 29% polystyrene; refer to Table 1 fordetails.

The polymer was hydrogenated to a residual olefin concentration of lessthan 0.15 meq/g and the catalyst was removed using techniques known inthe art. The polymer was recovered via steam stripping. The selectivelyhydrogenated block copolymer was tested for polymer composition,solution viscosity, and ODT. Results of the test are in Table 1. Theselectively hydrogenated block copolymer was tested for mechanicalproperties and melt index. The results are in Table 2.

Example 5

A selectively hydrogenated block copolymer prepared in a similar mannerto Examples 1-3 Example 5 has a lower polystyrene concentration andlower coupling efficiency than the previous examples; refer to Tables 1and 2 for more details.

Table 1 lists the styrene block molecular weight, diene block molecularweight, coupling efficiency, polystyrene concentration, vinylconcentration, solution viscosity, and ODT for various examples. Theblock copolymers were tested for Brookfield viscosity and ODT wasmeasured using a Bohlin VOR rheometer.

TABLE 1 Polymer Composition, Solution Viscosity and ODT. Styrene DieneCoupling Polystyrene Vinyl Solution Block MW Block MW Efficiency ContentAmount Viscosity ODT Polymer (g/mol) (g/mol) (wt %) (wt %) (wt %) (cP)(° C.) Example 1 5,200 E1 = 11,500 92 36.5 79 23 170 Example 2 4,900 E1= 12,000 87 32.4 79 25 170 Example 3 4,900 E1 = 12,000 76 35 76 21 170Example 4 4,500 &  E = 23,500 — 29 76 42 220 5,500 Example 5 4500 E1 =15,000 51 23 78 24 160 Comp. 5,000 E1 = 20,000 90 20 78 92 170 Example 6Comp. 5,600 E1 = 13,000 90 30 38 583 250 Example 7

The 100% modulus, tensile strength, elongation to break and melt flowfor various examples and comparative examples are in Table 2. Tensileproperties were measured on compression molded film samples accordingASTM D412. A Mini D die was used to cut the specimens and a 50 mm/min.tensile rate was used. Partially hydrogenated block copolymers ofcomparative examples 1 and 2 were prepared and tested. Comparativeexample 6 is a 20 wt. % styrene, high vinyl SEBS block copolymer that isa considered to be one of the lowest viscosity block polymerscommercially available; refer to Table 1 and 2 for details. However,relative to comparative example 5, examples 1-4 are significantly lowerviscosity than comparative example 1; see the solution viscosity inTable 1 and the melt index in Table 2.

In addition, even though they are low molecular weight compared tocomparative example 5, examples 1-4 have reasonable modulus, elongationto break and tensile strength; refer to Table 2. Likewise, with similarmolecular weights to comparative example 7 (Table 1), examples 1-4 aresignificantly lower viscosity due to the higher vinyl concentration.However, the ODT was significantly, and unexpectedly lower, for examples1-4 compared to comparative example 6, even though the polystyreneconcentrations for examples 1-4 are equal or higher than comparativeexample 2. A lower ODT improves processability (reduced pressure, higherthroughput rates, etc.) at normal polymer processing temperatures (200to 250 C).

TABLE 2 Mechanical Properties and Melt Index (MI) MI at 100% ElongationTensile 190° C. and Modulus to Break Strength 2.16 kg Polymer (MPa) (%)(MPa) (g/10 min.) Example 1 2.4 510 8.3 240 Example 2 2.3 500 6.3 388Example 3 1.9 520 5.7 464 Example 4 2.7 450 6.9 90 Example 5 0.9 600 3.1770 Comparative 1.2 780 10.3 38 Example 6 Comparative 2.7 560 39.3 3.4Example 7

Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one with skill in theart to which the disclosed disclosure belongs. As used herein, the term“comprising” and variations thereof as used herein is used synonymouslywith the term “including” and variations thereof and are open,non-limiting terms, meaning including elements or steps that areidentified following that term, but any such elements or steps are notexhaustive, and an embodiment can include other elements or steps.Although the terms “comprising” and “including” have been used herein todescribe various aspects, the terms “consisting essentially of” and“consisting of” can be used in place of “comprising” and “including” toprovide for more specific aspects of the disclosure and are alsodisclosed.

For the purposes of this specification and appended claims, unlessotherwise indicated, all numbers expressing quantities, percentages orproportions, and other numerical values used in the specification andclaims, are to be understood as being modified in all instances by theterm “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that can vary depending upon thedesired properties sought to be obtained. It is noted that, as used inthis specification and the appended claims, the singular forms “a,”“an,” and “the,” include plural references unless expressly andunequivocally limited to one referent. As used herein, the term“include” and its grammatical variants are intended to be non-limiting,such that recitation of items in a list is not to the exclusion of otherlike items that can be substituted or added to the listed items.

Unless otherwise specified, the recitation of a genus of elements,materials or other components, from which an individual component ormixture of components can be selected, is intended to include allpossible sub-generic combinations of the listed components and mixturesthereof.

The patentable scope is defined by the claims, and can include otherexamples that occur to those skilled in the art. Such other examples areintended to be within the scope of the claims if they have structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements with insubstantialdifferences from the literal languages of the claims. To an extent notinconsistent herewith, all citations referred to herein are herebyincorporated by reference.

1. A selectively hydrogenated block copolymer having an S block and an Eor E₁ block and having a general formula: S-E-S, (S-E₁)_(n)X, ormixtures thereof, wherein: n has a value of 2 to 6; X is a couplingagent residue; molecular weight of the S block is 4,400 to 5,600 g/mol;a solution viscosity of the block copolymer is less than 80 centipoise(cP); polystyrene content in the block copolymer is 25 to 40 wt. %; upto 50 wt. % of diblock units in the block copolymer with a generalformula S-E or S-E₁; wherein prior to hydrogenation: the S block is apolystyrene block; the E block is a polydiene block selected from thegroup consisting of polybutadiene, polyisoprene and mixtures thereof,and having a molecular weight of from 18,000 to 36,000 g/mol; the E₁block is a polydiene block selected from the group consisting ofpolybutadiene, polyisoprene and mixtures thereof, and having a molecularweight of from 9,000 to 18,000 g/mol; total vinyl content of thepolydiene block is 60 to 85%; and wherein subsequent to hydrogenation:0-10 percent of styrene double bonds in the block copolymer are reduced,and at least 80 percent of conjugated diene double bonds in the blockcopolymer are reduced.
 2. The block copolymer of claim 1, wherein theblock copolymer has an order-disorder temperature (ODT) of less than230° C.
 3. The block copolymer of claim 1, wherein the block copolymerhas a formula S-E-S, with less than 10 wt. % of a diblock copolymer offormula S-E.
 4. The block copolymer of claim 1, wherein the blockcopolymer has a formula (S-E₁)_(n)X, with between 5 and 50 wt. % of adiblock copolymer of formula S-E₁.
 5. The block copolymer of claim 1,wherein the coupling agent is selected from the group of methylbenzoate, silicon tetrachloride, alkoxy silanes, polyepoxides,polyisocyanates, polyimines, polyaldehydes, polyketones, polyanhydrides,polyesters, polyhalides, diesters, methoxy silanes, divinyl benzene,1,3,5-benzenetricarboxylic acid trichloride, glycidoxytrimethoxysilanes, oxydipropylbis(trimethoxy silane), and mixtures thereof.
 6. Theblock copolymer of claim 1, wherein the block copolymer has a formula ofS-E-S, and a solution viscosity ranging from 10 cP to 80 cP, measured asa 25 wt. % solution in toluene at 25° C.
 7. The block copolymer of claim1, wherein the block copolymer has a formula of (S-E₁)_(n)X, and asolution viscosity ranging from 10 to 50 cP, measured as a 25 wt. %solution in toluene at 25° C.
 8. The block copolymer of claim 1, whereinthe block copolymer has a melt index from 80 to 1300 g/10 min. at 190°C. and 2.16 kg weight, according to ASTM D1238.
 9. The block copolymerof claim 1 wherein the block copolymer has an elongation at break of atleast 300%, as measured on compression molded films according to ASTMD412.
 10. The block copolymer of claim 1 wherein the block copolymer hasa tensile strength of at least 1.5 Mpa, as measured on compressionmolded films according to ASTM D412.
 11. The block copolymer of claim 1wherein the block copolymer is functionalized with a functional groupselected from fumaric acid, itaconic acid, citraconic acid, acrylicacid, maleic anhydride, itaconic anhydride, citraconic anhydride, andtheir derivatives and derivatives thereof.
 12. The block copolymer ofclaim 11, wherein the block copolymer is functionalized by graftingmaleic anhydride onto the block copolymer.
 13. An adhesive compositioncomprising: 0 to about 80 wt. % of a poly-alpha-olefin 10 to about 60wt. of a tackifying resin, and 10 to about 50 wt. % of the hydrogenatedblock copolymer of claim
 1. 14. A composition comprising: theselectively hydrogenated block copolymer of claim 1; 0.001 to 90 wt. %of an additive selected from olefin polymers, thermoplasticpolyurethane, thermoplastic copolyester, styrene polymers, thermoplasticelastomers, tackifying resins, polymer extending oil, waxes, fillers,lubricants, stabilizers, engineering thermoplastic resins, and mixturesthereof.
 15. The composition of claim 14, wherein the additive is a highflow polyolefin having a melt flow rate of >40 g/10 min.
 16. Thecomposition of claim 14, wherein the selectively hydrogenated blockcopolymer has an order-disorder temperature (ODT) of 140-230° C.
 17. Anarticle comprising the composition of claim 14, wherein the article isselected from the group of toys, medical devices, films, tubing,profiles, 3D printed article, sheet, coating, band, strip, molding,tube, foam, tape, fabric, thread, filament, ribbon, fibers, fibrous web,overmolded automotive parts, dipped goods, sheet molded articles, hotmelt adhesives, tie-layers, roofing sheets, membranes, tire treads, andtire inner layers.
 18. The article of claim 17, wherein the article isformed by injection molding, overmolding, dipping, extrusion,roto-molding, slush molding, fiber spinning, film making, 3D printing orfoaming.
 19. A composition comprising: a selectively hydrogenated blockcopolymer having an S block and an E or E₁ block and having the generalformula S-E-S, (S-E₁)_(n)X or mixtures thereof, wherein: n has a valueof 2 to 6, X is a coupling agent residue, styrene content of the blockcopolymer is 29 to 37 wt. %, a viscosity in the range of 10 to 80centipoise (cP), measured as a 25 wt. % solution in toluene at 25° C.;wherein prior to hydrogenation the S block is a polystyrene block, the Eblock is a polydiene block, selected from the group consisting ofpolybutadiene, polyisoprene and mixtures thereof, having a molecularweight of from 18,000 to 36,000 g/mol, the E₁ block is a polydieneblock, selected from the group consisting of polybutadiene, polyisopreneand mixtures thereof, having a molecular weight of from 9,000 to 18,000g/mol, total vinyl content of the polydiene blocks is 70 to 85%; whereinsubsequent to hydrogenation 0-10 percent of the styrene double bondshave been hydrogenated; and at least 80 percent of conjugated dienedouble bonds in the block copolymer are reduced; and wherein the blockcopolymer is functionalized with 0.1 to 10 wt. % of a monomer selectedfrom fumaric acid, itaconic acid, citraconic acid, acrylic acid, maleicanhydride, itaconic anhydride, citraconic anhydride, and derivativesthereof.
 20. The composition of claim 19, wherein the selectivelyhydrogenated block copolymer has an order-disorder temperature (ODT) ofless than 230° C.